Summarising - Assignment Example

Genome Scientists have achieved clinically meaningful results by treating hemophilia in mice using genome editing. Researchers used two versions of genetically engineered virus of Adeno-Associated Virus. One that carried enzymes that cut DNA in an exact spot within living mice’s liver cells and another that carried a replacement gene to the exact cut spot within the DNA sequence. According to hematologist Katherine High, M.D at The Children’s Hospital of Philadelphia, the research established that genome editing could correct a genetic defect in vivo delivery of zinc finger nucleases (Li).

High and Sangamo BioSciences, Inc., scientists used Zinc Finger Nucleases (ZFNs) genetically engineered enzymes that act as molecular word processors to edit mutated sequences of DNA. Since scientists have learnt how to design custom-matched ZFNs to a specific gene location, they designed ZFNs specifically for factor nine genes (F9) and used it in conjunction with a DNA sequence to restore the normal gene function lost in hemophilia. ZFNs are more advantageous compared to conventional genes since they target a precise place in a sequence of chromosomes (High).

Conventional genes may deliver a replacement gene to an unwanted location resulting to bypassing of normal biological regulatory components controlling the gene hence cause risk of “insertion mutagenesis”.An inherited single-gene mutation in hemophilia impairs a patient’s ability to produce blood-clotting proteins. This results to spontaneous life-threatening bleeding episodes. Hemophilia has two major forms, A and B, which occurs solely in males. They result from lack of clotting factors VIII and IX respectively.

In a recent study, researchers used genetic engineering to produce a hemophilia B mouse. Prior treatment, the mouse depicted no levels of clotting factor IX since previous studies by different researchers shown that ZFNs could accomplish genome editing if injected into mice for sickle cell disease treatment. However, the ex living animal approach was not feasible for many human genetic diseases affecting whole organ system (Shangzhen). Therefore, the current study was testing genome-editing effectiveness when performed in a vivo.

The researchers designed two vector versions using Adeno-associated virus. One vector ferried ZFNs for editing while the other delivered a correctly functioning version of the F9 gene. Since different mutations in the same gene may cause hemophilia, the process replaced seven different coding sequences, covering 95% of the disease-carrying mutations in hemophilia B. Researchers administered gene therapy vector into a mouse liver whereby, the liver that received ZFNs/gene combination produced enough clotting factor that reduced blood-clotting times to nearly normal level (Philip).

However, the liver that received vectors lacking ZFNs or F9 mini-genes had no significant improvements in blood-clotting times. In conclusion, results showed no toxic effects on growth or liver functioning depicting that genome editing is possible in vivo. High proposed further studies in order to translate these findings into safe, effective treatments for hemophilia and other single-gene diseases in human. Clinical translation of genetic therapies from mouse models to humans was a lengthy process, but achieving positive results made it worth.

For greater genome editing results, therapeutic procedure needs to mature (High). Work CitedHojun Li, Virginia Haurigot, Yannick Doyon, Tianjian Li, Sunnie Y. Wong, Anand S. Bhagwat, Nirav Malani, Xavier M. Anguela, Rajiv Sharma, Lacramiora Ivanciu, Samuel L. Murphy, Jonathan D. Finn, Fayaz R. Khazi, Shangzhen Zhou, David E. Paschon, Edward J. Rebar, Frederic D. Bushman, Philip D. Gregory, Michael C. Holmes, Katherine A. High. In vivo genome editing restores haemostasis in a mouse model of haemophilia.

Nature, 2011; DOI: 10.1038/nature10177.